Adjustable draw key



R. K- WADE ADJUSTABLE DRAW KEY Filed plil 27, 194e N\`lo,

Patented Aug. 30, 1949 UNITED STATES PATENT OFFICE 2,480,429 ADJUSTABLE DRAW- KEY Roger Knowles Wade, Fond du Lac, Wis. Application April 27, 1946, Serial No. 655,571

i claim. 1

This invention relates to expandable draw keys and resides specifically in an improved form of the same in which a transversely slidable draw tongue is mounted within a draw key body in inclined Vplane relationship to a longitudinally positionable actuator within the key body, the `actuator being controllable as to its position by ascrew positioner preferably of the dierentlal typevaccessible from the exterior of the key body.

Heretofore expandable draw keys have :been constructed in various forms and have been employed for various purposes. In the case of keys intended to hold tapered shank tools in place in machine tool spindles expandable draw keys have not heretofore found favor. The common practice has heretofore been to hold such tapered shank tools in place with tapered keys driven into place. is damaging to the spindle, its bearings, the tool and the key itself.

It is an object of this invention to provide an expandable draw key of such simplicity, reliability and convenience in its use as to encourage operators of machine tools to abandon the tapered key and its need for harmful hammering.

This invention is herein described by reference to the accompanying drawing in which there is set forth by way of illustration and not of limitation one form in which the apparatus of this invention may be embodied.

In the drawing:

Fig. 1 is a side view in elevation and in section of a draw key constructed in accordance with this invention said section being viewed through the plane I--I indicated in Fig. 2;

Fig. 2 is an end view in elevation and in section of the key shown in Fig. 1 the same being viewed through the plane 2--2 there indicated;

Fig. 3 is a side view in elevation on a reduced scale of the key shown in Fig. 1 shown in place in a spindle the latter being shown partly broken away and in section; and

Fig. 4 is an end view in elevation of the key shown in Fig. 1.

Referring now to the drawing the form of the key of this invention there shown comprises a key body I of elongated, attened form with rounded upper and lower edges. The key body I has formed in it a transverse slot or recess 2 extending from one edge downwardly beyond the center of the key body I until it intercepts a 1ongitudinal channel 3 also formed within the key body I as shown. The longitudinal channel 3 is in the form of a cylindrical bore the left hand The hammering which this entailsY 2 end of which is provided with an internal thread 4.

Mounted to ffreely slide transversely in the recess 2 is a draw tongue 5 the lower or inner face of which is'inclined'as shown at 6. As` more clearly appears in Fig. 2 there is formed in the tongue 5 along its inclined face 6 a circular dovetail opening 'I running parallel with theface 6 and emerging therefrom.

Mounted to slide longitudinally in the channel 3 is an actuator 8 of' cylindrical form closely tting the bore of the channel 3. The actuator 8 is shaped so as to present an inclined face 9 in sliding inclined plane relationship to the inclined face 6 of the tongue 5. Projecting upwardly from the inclined face 9 and formed integrally therewith is a dovetail I0 shaped for interfitting engagement with the dovetail slot 1. By reason of this construction longitudinal movement of the actuator 8 compels not only expansion of the tongue 5, if the actuator moves to the right, but positiveretraction of the same as well, when the actuator 8 moves toward the left.

In order to provide for convenient positioning of the actuator 8 a screw II is mounted in threaded engagement with thread 4. The screw I'l is provided with a hexagonal end socket I2 which may be engaged by a wrench introduced through the reduced end opening I3 in the channel 3. The screw I l itself is provided with a central bore internally threaded as indicated at I4. The thread I4 is formed as shown to be of opposite hand to the thread 4 and of different pitch therefrom. Threadedly received within the thread I4 is a threaded shank I5 formed as a part of the actuator 8.

By reason of the arrangement of the threads above described a differential action takes place upon rotation of the screw II.

For example, if the screw II be turned so as to cause it to advance toward the right, its rate of advance per turn will be equal to the pitch of its thread. At the same time the screw I'5 will move relatively with respect to the screw I l toward the left an amount equal to the pitch oi' the thread of screw I5. Since this is a smaller amount than the advance toward the right of the screw II a net motion toward the right of the actuator 8 takes place and the tongue 5 is caused to move outwardly from the key body I. Rotation of .the screw Il in the opposite direction produces an opposite motion of the tongue 5. In this way a very powerful mechanical advantage is made available for expansion of the key and a natural 3 and normal expansion on right hand rotation is produced.

After the parts are assembled it is preferred that a plug I6 held in place by a pin Il be lnserted as shown.

As appears in Fig. 3 one convenient intended use of the key of this invention is to hold the tapered shank I8 of a boring or milling tool in the tapered socket provided therefor in a spindle nose I'9. Under these circumstances the transverse slot 20 of the nose I9 is engaged by the key body l while the transverse slot 2l of the tool shank I8 is engaged by the tongue 5. It may be readily observed that the key body I can be quickly inserted and a wrench .applied to the screw l l to bring the parts to thepos'ition shown. In this way the tool shank i8 is quickly :flocked in place without any damaging hammering being necessary and when it is necessary to remove the tool, the tongue can be retracted quickly also without hammering.

I claim:

In Ean :expandable draw key .a'key body zhaving a transversely extending draw 'tongue -recess 'and a longitudinally extending actuator Achannel .1intersecting .-said recess, a transversely slidable -draw Atongue received Vwithin and closely fitting said recess `conned to transverse sliding movement thereby and having :an inner inclined face, van :actuator .longitudinally :movable in :said chan- AREFERENCES CITED The 1foll'owi-ng references are of record in the file of this patent:

UNITED STATES PATENTS JNrnziber Name Date 298;903 `Seaman May '20, T884 `158241729 Miller Sept. l22, 15981 1,849,137 7 Newton Mar. i5, 1932 '2,237,230 Johnson Apr. 1, 1-'94'1 Y FOREIGN PATENTS Number vCountry Date I51495366 Germany Apr. 22, f1'925 

